title: Principal component analysis of PiB distribution in Parkinson and Alzheimer diseases.
abstract: OBJECTIVE
  To use principal component analyses (PCA) of Pittsburgh compound B (PiB) PET imaging to determine whether the pattern of in vivo β-amyloid (Aβ) in Parkinson disease (PD) with cognitive impairment is similar to the pattern found in symptomatic Alzheimer disease (AD).
  
  
  METHODS
  PiB PET scans were obtained from participants with PD with cognitive impairment (n = 53), participants with symptomatic AD (n = 35), and age-matched controls (n = 67). All were assessed using the Clinical Dementia Rating and APOE genotype was determined in 137 participants. PCA was used to (1) determine the PiB binding pattern in AD, (2) determine a possible unique PD pattern, and (3) directly compare the PiB binding patterns in PD and AD groups.
  
  
  RESULTS
  The first 2 principal components (PC1 and PC2) significantly separated the AD and control participants (p < 0.001). Participants with PD with cognitive impairment also were significantly different from participants with symptomatic AD on both components (p < 0.001). However, there was no difference between PD and controls on either component. Even those participants with PD with elevated mean cortical binding potentials were significantly different from participants with AD on both components.
  
  
  CONCLUSIONS
  Using PCA, we demonstrated that participants with PD with cognitive impairment do not exhibit the same PiB binding pattern as participants with AD. These data suggest that Aβ deposition may play a different pathophysiologic role in the cognitive impairment of PD compared to that in AD.
authors.affiliation: Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA. meghanc@npg.wustl.edu
authors.forename: Meghan C
authors.initials: MC
authors.lastname: Campbell
authors.forename: Joanne
authors.initials: J
authors.lastname: Markham
authors.forename: Hubert
authors.initials: H
authors.lastname: Flores
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Hartlein
authors.forename: Alison M
authors.initials: AM
authors.lastname: Goate
authors.forename: Nigel J
authors.initials: NJ
authors.lastname: Cairns
authors.forename: Tom O
authors.initials: TO
authors.lastname: Videen
authors.forename: Joel S
authors.initials: JS
authors.lastname: Perlmutter
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging* / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000378:metabolism; D000814:Aniline Compounds; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000378:metabolism; D049268:Positron-Emission Tomography / Q000379:methods; D025341:Principal Component Analysis / Q000379:methods*; D011485:Protein Binding / Q000502:physiology; D013844:Thiazoles
chemical_list: C475519:2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole; D016229:Amyloid beta-Peptides; D000814:Aniline Compounds; D013844:Thiazoles